PHILADELPHIA (CBS) – Veterinarians around the country are suddenly seeing spayed and neutered pets becoming hormonal, and certain topical creams used by humans appear to be the reason.

Veterinarians say estrogen creams appear to be the most common contributor to animal hormonal disorders.

According to Dr. Margret Casal, with the Ryan Veterinary Hospital at the University of Pennsylvania, a dog or cat could lick the cream off an owner’s skin or simply absorb it through their skin.

“So that will elicit in a female dog, usually, signs of going into heat, maybe some hair loss, and a funky hair coat, change in behavior,” Dr. Casal said.  “The same thing will go for male dogs — obviously male dogs don’t go into heat but may show a change in behavior, hair loss, or a change in hair coat.”

And Casal says estrogen exposure, over a long period, can be fatal to dogs.

“In the worst of all cases it can actually wipe out the bone marrow, and the bone marrow is a source of all the white and red blood cells,” she noted.

According to Dr. Casal, the more people use the hormone creams the more likely vets will see the hormonal disorder in pets, now that it has been identified.

Reported by John McDevitt, KYW Newsradio 1060.